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Environmental pollution indicated by the presence of P M 2.5 particulate matter varies based on prevailing atmospheric conditions described by certain meteorological variables. Consequently, it is important to understand atmospheric behavior in areas such as the Aburrá Valley, which experiences recurrent pollution events twice a year. This study examines the behavior of specific meteorological variables and P M 2.5 particulate matter in the Aburrá Valley. By using statistical analysis tools such as correlation coefficients, principal component analysis (PCA), and multiple linear regression models, the research identifies relationships between P M 2.5 and daily cycles of temperature, rainfall, radiation, and wind speed and direction. Datasets were analyzed considering periods before and after the COVID-19 lockdown (pre-pandemic and pandemic, respectively), and specific pollution events were also analyzed. Furthermore, this work considers the relationships between P M 2.5 and meteorological variables, contrasting the pre-pandemic and pandemic periods. This study characterizes diurnal cycles of meteorological variables and their relationship with P M 2.5 . There are consistent patterns among temperature, atmospheric boundary layer (ABL) height, and solar radiation, whereas precipitation and relative humidity show the opposite behavior. P M 2.5 exhibits similar relative frequency functions during both daytime and nighttime, regardless of rainfall. An inverse relationship is noted between P M 2.5 levels and ABL height at different times of the day. Moreover, the PCA results show that the first principal component explains around 60% of the total variance in the hydrometeorological data. The second PC explains 10%, and the rest of the variance is distributed among the other three to eight PCs. In this sense, there is no significant difference between the two PCAs with hydrometeorological data from a pre-pandemic period and a COVID-19 pandemic period. Multiple regression analysis indicates a significant and consistent dependence of P M 2.5 on temperature and solar radiation across both analyzed periods. The application of Generalized Additive Models (GAMs) to our dataset yielded promising results, reflecting the complex relationship between meteorological variables and P M 2.5 concentrations. The metrics obtained from the GAM were as follows: Mean Squared Error (MSE) of 98.04, Root Mean Squared Error (RMSE) of 9.90, R-squared (R2) of 0.24, Akaike Information Criterion (AIC) of 110,051.34, and Bayesian Information Criterion (BIC) of 110,140.63. In comparison, the linear regression model exhibited slightly higher MSE (100.49), RMSE (10.02), and lower R-squared (0.22), with AIC and BIC values of 110,407.45 and 110,460.67, respectively. Although the improvement in performance metrics from GAM over the linear model is not conclusive, they indicate a better fit for the complexity of atmospheric dynamics influencing P M 2.5 levels. These findings underscore the intricate interplay of meteorological factors and particulate matter concentration, reinforcing the necessity for advanced modeling techniques in environmental studies. This work presents new insights that enhance the diagnosis, understanding, and modeling of environmental pollution, thereby supporting informed decision-making and strengthening management efforts. [ABSTRACT FROM AUTHOR]

Antecedentes: Didelphis spp. es un género de marsupiales americanos didelfimorfos descritos como especies sinantrópicas y posibles candidatos a la clasificación de especies sombrilla‚ por su importante rol en el ambiente rural y urbano‚ cumpliendo funciones de control poblacional y dispersores de semillas‚ aunque son considerados focos zoonóticos y por error‚ una plaga‚ al compartir ambientes con el humano. A pesar de ello‚ Colombia no cuenta con grandes datos sobre las enfermedades más prevalentes en ellos. Objetivo: describir macroscópicamente hallazgos de necropsia en varios individuos y en diferentes sistemas orgánicos de Didelphis spp. Métodos: 14 zarigüeyas de diferentes sexos‚ grupos etarios y etapas biológicas fueron entregadas por la autoridad ambiental Corpocaldas al Laboratorio de Patología Veterinaria de la Universidad de Caldas para necropsia. Resultados: 8 de 14 (57‚1 %) animales‚ presentaron lesiones en el sistema cardiovascular (congestión‚ hemorragia tipo hepatización‚ hemopericardio‚ hipertrofia cardiaca izquierda‚ entre otros); 7 de 14 (50 %)‚ lesiones en la piel (laceraciones‚ ulceras‚ heridas abiertas‚ nódulos‚ alopecia‚ entre otras); 6 de 14 (42‚9 %) en el aparato digestivo (gastritis‚ úlceras‚ parásitos‚ linfadenopatías‚ entre otras); 4 de 14 (28‚6 %) tenían lesiones en el aparato reproductor y endocrino (piómetra‚ quistes ováricos y hasta un posible caso de intersexo); 2 de 14 (14‚3 %) animales lesiones en aparato locomotor (fracturas por trauma o atropellamiento) y 1 animal (7‚1 %) tenía lesiones en riñones que mostraron hemorragias y disminución proporcional de corteza y médula. El sistema nervioso solo se revisó en tres animales sin encontrar lesiones aparentes. En general en líquidos corporales se observó alto contenido bacteriano y gran cantidad de procesos inflamatorios con alta respuesta inmunológica. Conclusiones: se espera con los resultados finales aportar información médico-científica relevante‚ novedosa y concluyente sobre la salud de las zarigüeyas a nivel regional y nacional para ampliar el conocimiento sobre estas especies‚ aportando a futuros estudios epidemiológicos‚ biológicos y medico veterinarios. [ABSTRACT FROM AUTHOR]